How to change shutter speed on Nikon D90?

I was borrowing a friend's D90 (I usually use Canon) and I had two issues with it:
1. How do you change shutter speed while on Manual mode? The front dial only changes the f-stop and not the shutter speed.
2. The camera takes a significant amount of time to focus after I click the shutter button. Is there some sort of continuous mode (like on Canon) that the D90 can be switched to?

The simplest way to answer your questions is go to the Nikon site and download the owner's manual for that camera.

I'm a Canon user as well and I really enjoy my cameras. By the way you can, if you need to, download manuals for Canon cameras at their site as well.

Rotate the main command dial to choose your desired shutter speed. Available in Shutter-priority & Manual shooting mode only.

When in manual mode, front dial is for aperture; rear dial, next to where your thumb rests, adjusts shutter speed.

Focus speed is dependent on a number of things. Could be that the lens is slow to focus or you are trying to focus on something with low contrast. Focus mechanisms require contrasting edges. You can change the focus mode to AF-C which is the continuous mode (other modes are AF-A and AF-S). I believe the D90 has a dedicated button to change focus mode. Otherwise, consult the manual which is available on Nikon's web site.AF-C mode can reduce battery life since the focus mechanism is always operating when the shutter release is depressed half way.

1. Rotate the main control dial (the one at the back)

2. There's an AF button on the top right hand side of the camera. Change it to "AF-C" for continuos autofocus.